(a) Field of the Invention
The present invention relates to a driving method of a plasma display panel (PDP).
(b) Description of the Related Art
The PDP is a flat display device for displaying characters or images using plasma caused by gas discharge, and several tens to several millions of pixels are arranged in a matrix format on the PDP according to the PDP size. The PDP is classified into an AC type and a DC type according to a driving voltage waveform and structure of a discharge cell.
In the DC PDP, electrodes are directly exposed in a discharge space and thus current directly flows in the discharge space when voltage is applied. Thus a resistor is required to restrict the current. However, in the AC PDP, electrodes are covered with a dielectric layer. Thus, naturally occurring capacitance restricts the current, and the electrodes are protected from ion impulses when discharge occurs. The life of the AC PDP is therefore longer than the life of the DC PDP.
The AC PDP includes a plurality of scan electrodes and a plurality of sustain electrodes which are arranged in parallel on one substrate. A plurality of address electrodes are arranged on an opposite substrate and lie in a direction perpendicular to the scan electrodes and sustain electrodes. The sustain electrodes are arranged corresponding to each scan electrode. One end of the sustain electrodes are commonly connected.
FIG. 1 is a partial perspective view of an AC PDP. The PDP includes two glass substrates 1, 6, which are arranged in a face-to-face relationship. On the first substrate 1, pairs of a scan electrode 4 and a sustain electrode 5 which are covered with a dielectric layer 2 and a protective layer 3 are arranged in parallel. On the second substrate 6, a plurality of address electrodes 8, which are covered with an insulating layer 7, are arranged. Barrier ribs 9 are formed in parallel with the address electrodes 8 on the insulating layer 7. A fluorescent material 13 is formed on the surface of the insulating layer 7 between the barrier ribs 9 and on both sides of the barrier ribs 9. The glass substrates 1, 6 are arranged in a face-to-face relationship with a discharge space 11 formed therebetween, such that the scan electrodes 4 and the sustain electrodes 5 lie in a direction perpendicular to the address electrodes 8. A discharge space 11 at intersections of the address electrodes 8 and the pairs of scan electrode 4 and sustain electrode 5 forms discharge cells 12.
FIG. 2 shows a driving waveform of an AC PDP. Generally, in the PDP, one frame is divided into a plurality of subfields, and is driven. Each subfield includes a reset period, an address period, a sustain period, and an erase period. The reset period is a period for erasing wall charges that have been formed by a previous sustain discharge, and setting up a new wall charge in order to stably perform a next address discharge. The address period is a period for selecting cells being turned on and cells being turned off, and accumulating a wall charge on cells being turned on (addressed cell). The sustain period is a period for performing a sustain discharge to display a video image on an addressed cell. The erase period is a period for decreasing the wall charge of the discharge cell and terminating the sustain discharge.
To achieve the above operation, as shown in FIG. 2, a sustain discharge pulse is alternatingly applied to a scan electrode and a sustain electrode in the sustain period, and a gradually rising ramp voltage is applied to the sustain electrode X in the erase period following the sustain period. Then, a reset waveform is applied to the scan electrode Y, under a condition that the address electrode A is maintained at a ground (0V) voltage and the sustain electrode X is biased at a predetermined voltage. Then, in the address period, an address waveform is applied to the scan electrode Y and the address electrode A to select a discharge cell that is desired to be displayed when the scan electrode Y and the sustain electrode X are respectively maintained at the predetermined voltage.
However, for the conventional driving method of the PDP, a scan driving board for driving a scan electrode Y, a sustain driving board for driving a sustain electrode X and an address driving board for driving an address electrode A are respectively required. Thus, three driving boards are required to be built in a chassis base, increasing the cost.